30 FISHES AND FISHERIES OF THE IRISH SEA. 
XL 
upon larval Crustacea. Up to the age of about a month, the little fish is perfectly 
symmetrical; then that remarkable rotation of the head sets in, which results in both 
eyes coming to lie upon the coloured side of the animal. The complete metamorphosis 
takes about two weeks, and the little animal is then 13 mm. in length. The fish, now 
flattened and coloured like the adult, rests upon the left side, and feeds chiefly upon 
Copepoda. A somewhat rare Copepod, called $Fonesiella hyene, which was not known 
until Mr. I. C. Thompson found and described it from our district, is apparently a 
favourite food of young plaice at this period, since we frequently find it in their 
stomachs. When a size larger again, say from 3 cm. to 7 or 8 cm., the animal feeds 
upon small worms and upon the feebler Crustacea, such as Mysis, Later on again, and 
during the remainder of its life, the plaice feeds mainly on Lamellibranch Mollusca, such 
as Mactra and Donax, From the time of its metamorphosis onwards the plaice is a 
bottom-living fish, feeding on the ground, in which it frequently lies partially buried. It 
has small powers of migration, and in such a district as the Irish Sea is all its life 
exposed to man and liable to be captured. In its early youth it is harried by the 
shrimpers of all kinds along the shores, and in the estuaries, when it gets a little 
larger but is still immature, it is the object of an extensive fishery on the coast by 
means of stake nets, and on the in-shore grounds by trawlers; finally, in the open 
sea, it is one of the chief sources of revenue to the deep-sea trawler. In this 
constant liability to be captured, it contrasts markedly with migratory fish, such as 
the herring and mackerel, and even with fish such as the cod, which at times pass 
beyond our local fishing operations. Hence the danger of over-fishing leading to a 
serious decrease of such an important food-fish as the plaice in British waters. 
Our Lancashire statistics, taken over the last 10 years, although in many respects not 
so continuous and complete as we should desire, give us many valuable items of information in 
regard to the distribution and abundance of young and old fishes at different seasons. The 
following extracts as to the plaice are of interest. They are all from hauls with the shrimp 
trawl :-— 
June 21st, 1893... a dteyshamt inn ... 510 plaice, about 1} inches long. 
August 11th, 1892 Bob An Fite Hie TG 2OOR a, afl 22 49 
) 56 300 $5 508 eho MD) oy ay Ane ae 
July roth, 1893... 560 *) ape sre; 200) Mais Ae a} ” 
July 11th, 1894 =... 58 9 ae EB yOSO) igs he 3 » 
August 7th, 1894 ... sae - a 500 SEO) or a 3h 45 
September 27th, 1895 .... Ulverstone Ch. aL O77 ants Ha ” 
October 15th, 1895 35 39 see 54a ess sarang ” 
October 23rd, 1894 .. Heysham 200 #3. 4,000) 84) eu! ” 
November 9th, 1894 6c 30 te aae63 OOOMEE opie ttt 
December 4th, 1894 S00 sf a segs OOM eS ” 
That gives an idea of the range in size of the little fish in the coastal ‘‘ nurseries,” 
where the minute plaice, which has just completed its metamorphosis, usually appears in May, 
and from which it gradually moves out into deeper water about the end of autumn. These 
times are, of course, liable to some variation, from year to year, according to the season and 
state of the weather. Then larger, but still immature fish, say from 5 to 11 or 12 inches in 
length, are found a little further out along the banks, such as just outside the Blackpool 
ground, and outside the Liverpool Bar, in depths of about 10 fathoms. Larger mature 
